“Unlike the Government we believe that headteachers, not bureaucrats, should be running schools,” he said.

“For too long teachers and schools have been held back by bureaucracy, political interference and a lack of freedom. Only a Conservative government will give teachers the powers they need to provide a high quality education for all.”

Under plans, the Tories will allow any state primary or secondary school rated “outstanding” by Ofsted to convert into an academy with immediate effect.

The party has pledged to legislate within weeks of taking power to sweep away restrictions on the creation of new schools.

It will remove the power of councils to “veto” the opening of academies, which are run independently of local authorities, giving them more freedom to hire staff, set wages, alter the curriculum and change the length of the school day. The Tories have also pledged to allow schools to offer alternative qualifications, such as the International GCSE.

In a study published on Friday, the Times Educational Supplement surveyed a sample of primary and secondary school headteachers across England to gauge support for the move.

Research suggested that more than 500 top schools would opt out of the state system from September to become academies. A further 1,500 schools would consider the change, the study indicated.

It would lead to a dramatic expansion in the number of academies from the 203 opened so far under Labour to around 700 within five months.

Around a third of headteachers of outstanding schools said they would reject the offer outright.

The disclosure sparked anger among unions who claim academies undermine teachers’ rights and lead to the privatisation of state education by the backdoor. Teachers have already taken strike action to block the opening of academies in areas such as Basildon, Derby, Durham, Staffordshire, Tamworth and the London boroughs of Brent, Croydon and Newham.

John Bangs, the NUT’s head of education, told the TES: “It would be absolute chaos, particularly among primaries.”

Chris Keates, general secretary of the NASUWT, said: “What we are witnessing is the break up of state education. The national pay and conditions framework will go out of the window.

“We will be watching the weakest schools go to the wall and the staff and pupils in them left languishing.”